Insulating compound



ters Patent were granted to ine February 2,

UNITED ST TES JAMES B. \VILLIAMS, OF SAN FRANCISCO, CALIFORNIA.

. INSULATING PATENT OFFICE.

COMPOUND.

SPECIFICATION forming part of Letters Patent N 0. 420,648, datedFebruary 4, 1890. Application filed May 25, 1887. Serial No. 289,332.(No specimens.)

State of California, have invented a new and useful Composition ofMatter, of which the following is a specification.

My invent-ion relates to improvements in insulating compounds, and is animprovement upon the composition of matter for which Let- 1886, No.335,495, and for which I am about to filean application for a reissue.

Experiment has demonstrated that when i'ndia-rubber is used as aninsulating-covering for electric wires it can be subjected to atemperature of about 295 Fahrenheit before its insulation failsentirely, and that if the temperature does not exceed 120 Fahrenheit, orthereabout, its insulating properties can generally be depended upon.When guttapercha, however, is subjected to a temperatifre of 100Fahrenheit, its insulating properties begin to fail very rapidly, and ifthe temperature reaches 120 Fahrenheit, or thereabout, depending uponthe quality of the gutta-percha used, the insulating properties which itpossesses at ordinary atmospheric temperatures are almost entirely lost,and when electric conductors insulated with it or with compounds ofwhich it forms one of the principal ingredients are subjected toa'temperature of about 120 Fahrenheit large losses of the electriccurrent from such conductors by leakage through the insulatin g-covering occur by reason of the defectiveinsulation of the guttapercha.Further, if paraffine-Wax be used as an ingredient ofinsulating"compounds, instead of paraifineoil, the consistency of suchinsulating compounds is rendered firmer, and if a quantity of sulphup peadded to insulating compounds containing india-rubber in the proportionof one pound of sulphur to every eight to fifteen pounds of india-rubberthe india-rubber in such compounds is more durable after beingvulcanized than when preserved only by the admixture with it ofparaffine-oil and a resin or resins; and bituminous matter, if used asan ingredient of such insulating compounds, is rendered more d urableand requires a higher temperature to soften it after having beenincorporated in such compounds if the volatile and aqueous matters whichit contains are eliminated by the aid of heat before it is incorporatedin the K compound.

sulating material consists of india-rubber, paraffine, a resinous body,and sulphur, all in combination, and to which may be added or not whatmay be designated as inert material, which serves, if added, to hardenthe insulating material or compound and to lessen 1 its cost.

By parafiine-wax is meant ozocerite or mm- 3 eral wax, or, moreparticularly speaking, a substance having the consistency of wax, whosemain constituents are hydrocarbons, the

formula of which is CnHm-h, and by a resinous body is meant one of thosevegetable products commonly termed resins or gumresins, such as shellac,copal, colophony, sandarach, &c.

The inert material which should be added (it added at all) for thepurpose hereinbefore specified is silica or its equivalent, orbituminous matter, which is solid when cold. By equivalent of silica ismeant glass, asbestus,

solid steatite, kaolin, talc, and various car bonates, silicates, andoxides of the alkalies.

The paraffine which I prefer to use is that which is obtained fromozocerite or mineral wax, the resin which I prefer is shellac, and theinert material is silica or a silicate, although other paraffines,resins, and inert materials herein designated may be used instead of theones preferred with good results.

To make an insulating compound which, when properly applied toconductors of electricity and vulcanized, will be to a high degreedurable, flexible, and anhygroscopic, and will have a high insulationresistance, I take iudia-rubber, (forty parts, by weight,) paraffine,(fifteen parts, by weight,) shellac, (forty parts, by weight) andsulphur (five parts, by weight.) If a harder and less flexibleinsulating compound than that made according to the formula just givenis desired-for example, when the electric conductors to which it isapplied are to be placed in conduits or other receptacles where they areexpected to remain in one position for alength of time a quantity of theinert material is added to the formula above given, the quantity of theMy improved composition of matter for inr inert material to be thusadded varying ac-.

cording to the degree of hardness desired,

The greater the proportionate quantity of the inert material in theinsulating compound,

5 the less flexible and the more brittle it be-* comes. I thereforeprefer to keep the propertionate quantity of the inert material belowabout thirty per cent. of the whole composition after the inert materialis added, when the compound is to be applied to electric wires toinsulate them; but if the compound is to be used in the manufacture oftelegraphinsulators, or substitutes for hard rubber, the

proportionate quantity of the inert material may equal about fifty percent. of the whole composition.

I do not wish to restrict myself to the use of the exact proportions ofthe ingredients as specified in the formula above given, as

they are relative only and may be varied somewhat from those which arespecified without departing from the principle of my invention, andwithout greatly impairing the efficiency of the compound as aninsulating z 5 material. Neither do I wish to restrict myself to the useof silica or its equivalent or bituminous matter taken separately as theinert material for the purpose hereinbefore specified, because the twomay be combined 0 in various proportions with good results; but in caseboth are used the proportionate quantity of the two when combined shouldnot be greater than the proportionate quantity of either if takenseparately.

The compound made according to the for mula above given will be onewhich is suitable for ordinary purposes of insulation; but there arecases in which flexibility is not desiredas, for instance, when theinsulating 4o material is to be placed in tubes to insulate and maintainelectric conductorsin a fixed position in said tubes, in which case theindia-rubber may be used in smaller proportions than that specified.There are also 5 cases in which a very flexible and elasticinsulating-covering is desired, and in a such cases the india-rubber maybe used in larger proportions than that specified. I therefore desire toclaim, broadly, the combination of india-rubber, paraffine, and aresinous body in any proportions, as compounds formed by using the samein any proportions will be more or less useful as insulating material.

Before being incorporated into myinsulating compound the differentingredients of which it is composed should be cleansed of all foreignmatters which they may contain by any of the processes well known to theart, and the bituminous matter for use as an ingredient should be freedfrom the volatile and aqueous matters which it contains by subjecting itwhen in a powdered state to a temperature of from 300 to too" Fahrenheitin an open vessel, care being taken not to burn or char it while thevolatile and aque ous matters are being driven off.

To compound the ingredients of which my insulating compound is composed,I first dissolve the india-rubber in a volatile solvent which willdissolve it and parafiine-such as benzole or petroleum-naphtha-in astrong iron vessel provided with a tight-fitting metallic cover, whichcan be secured to the vessel by bolts or screws and surrounded by asteam-jacket heated to a temperature below the boiling-point of thesolvent used.

As the kind of vessel used and also the process to be adopted for makingsolutions of india-rubber are well known to the art, it is unnecessaryfor me to describe them in detail. I find that a compound ofindia-rubber and a solventin the proportion of about onehalf a pound ofindia-rubber to every gallon of solvent used is a convenient one tohandle during the process of incorporating the indiarubber andparafiine, to be hereinafter described.

After the india-rubbcr has been dissolved the solution is allowed tocool, when the proportionate quantity of paratfine in a coarselypowderedstate is added to the solution of india rubber. The mixture is then wellstirred and the cover of the vessel put on and secured and heat appliedby means of the steam-jacket until the para-fline is dissolved, whichwill usually require from five to fifteen minutes time. The solution ofindiarubber and paraffine is then allowed to cool, and when cooled ist'ansferred to a suitable distilling apparatus and the solventsdistilled at a temperature of about 200 Fahrenheit, the solvent vaporbeing condensed in a suit-able vessel and retained for future use. Byadopting this method of combining the india-rubber and parafiine theindia-rubher is reduced to a proper condition for incorporation with theremaining ingredients without subjecting it to a high temperature. Thecompound of india-rubber and parafline is then incorporated with theremaining ingredients, which are first reduced to a finelypowderedcondition by mixing all together by rollers heated by steam, and duringthe mixing all the solvent remaining in the compound of india-rubber andpara-nine after the distillation thereof is eliminated.

All of the ingredients of which the compound is composed may beincorporated by mixing them, when in a finely divided or powdered state,upon hot rollers, which is the process usually followed in the art ofcompounding india-rubber with other substances; but by so doing theindia-rubber is liable to deteriorate rapidly afterward, and also loseits insulating properties, whereas by combining it with the otheringredients substalr tially in the manner specified this subsequentdeterioration is largely prevented.

Before the electric conductors are coated with the insulating materialthey should be covered with a layer of cotton fiber and the fibersaturated with a varnish of shellac dissolved in alcohol in anyconvenient manner, the purpose of the varnish layer being to prevent asnearly as is possible the sulphur in the insulating material from comingin contact with or acting upon the material'of which the wires arecomposed during the vulcanization of the compound, and also to pre ventas nearly as possible moisture from creeping in between the wires andthe insulating compound while the insulating-Wires are in use. After thevarnish has become thoroughly dry the insulating compound is appliedover itin the same manner and by means of the same apparatus as isusually employed in coating electric wires with insulating compoundswhich become plastic when heated. The wires thus coated are then coveredwith one or more braids of cotton or other suitable fiber and the braidor braids saturated with the insulat-in g compound by passing the wiresthrough the compound held in a suitable vessel and kept in a liquidcondition by heat. The insulating compound is then vulcanized in asuitable chamber heated by steam to a temperature of from 270 to 280Fahrenheit for from one to three hours.

Besides being used as an insulating-covering for electric wires, thecompound herein described can be used in the manufacture of condensers,substitutes for hard rubber, and for insulators of telegraph and otherelectric wires.

I do not claim the mode of applying my compound to conductors ofelectricity, as this may be done by well-known methods; nor do I claimas any part of my invention any of the ingredients, taken separately, ofwhich my insulating compound is composed, as their insulating propertiesare well known.

It will be found that the compound herein described can be made morecheaply, can be more satisfactorily applied to conductors ofelectricity, will be more durable, and its insubody, sulphur, andbituminous matter which lating qualities are maintained at highertemperatures than in the case of the compound described in my saidLetters Patent before referred to.

lVhat I claim, and desire to secure by Letters Patent, is

1. An electric insulating compound which consists of india-rubber,parafline, and a resinous body, substantially as specified.

2. An electric insulating compound which consist-s of india-rubber,parafiine, a resinous body, and sulphur, substantially as specified. 3.An electric insulating compound which consists of india-rubber,parafline, a resinous body, sulphur and silica or its equivalent,substantially as specified.

4:. An electric insulating compound which consists of india-rubber,parafline, a resinous is solid when cold, substantially as specified.

5. An electric insulating compound which consists of india-rubber,para-ftine, a resinous body, sulphur, silica or its equivalent, andbituminous matter which is solid when cold, substantially as specified.

, G. Theprocessofmakingthe insulatingcompounds hereinabovc specified andclaimed, which consists in, first, dissolving the indiarubber in avolatile solvent; second, dissolving paraffine in the india-rubbersolution thus obtained; third, distilling from the solution ofindia-rubber and paraffine the volatile solvent, and, fourth,incorporating the resident compound of india-rubber and parai'fine withone or all of the remaining ingredients, all substantially as specified.

New York city, May 21, 1887.

JAMES B. \VILLIAMQ.

Witnesses:

CHAS. G. F. WAHLE, J11, J. E. HINDON HYDE.

